JPS62149788A - Blue pigment-coated phosphor - Google Patents

Abstract

PURPOSE:To obtain the titled phosphor capable of providing a color cathode ray tube coated with a phosphor film having excellent life characteristics, high contrast and high denseness, by coating a phosphor with a blue pigment prepd. by mixing ultramarine with a cobalt blue pigment in a particular proportion. CONSTITUTION:Ultramarine is mixed with 30-70wt%, pref. 43-56wt% cobalt blue pigment to obtain a blue pigment (A). A zinc sulfide phosphor (B) such as ZnS:AgCl, ZnS:AgAl is coated with the component A in an amt. of 0.5-10.0wt%, pref. 2-7wt% based on the component B.

Description

DETAILED DESCRIPTION OF THE INVENTION TECHNICAL FIELD OF THE INVENTION This invention relates to blue pigment coated phosphors for color television.

[Technical background of the invention and its problems]

In recent years, so-called pigment-coated phosphors, in which the surface of the phosphor is coated with a pigment that transmits the emitted color of the phosphor and absorbs other visible light, have been used in cathode ray tubes for color televisions in order to improve the contrast of the screen.

Pigments currently known as pigments for pigment-coated phosphors include Cobalt Blue Pigment 1, which is blue.

Red red color, cadmium selenide sulfate.

There are indium sulfide, etc., all of which have an average particle size of 0.05.
The particle size is adjusted to about 3 μm from 4 Itm to 15 μm.
Attach to μm phosphor. The pigments used in these phosphors for color cathode ray tubes are those that match the emission spectrum of the phosphor, and the better the coloring power of the pigment, the better the pigment. However, when it comes to actual use, cobalt aluminate is used instead of ultramarine, which has good pigment properties, as a blue pigment. This is because ultramarine blue fades with acid, so when coating it on the surface of a phosphor, it can only be used in a limited range from neutral to alkaline. ■Because ultramarine blue fades when exposed to heat, it cannot be absorbed by the temperatures used for sealing in the cathode ray tube manufacturing process. ■The dichromate used when forming the phosphor film has a strong oxidizing effect and contains w amount of hexavalent chromium.
One example of this is that ultramarine blue color fades even at relatively low temperatures. Among these fading colors of ultramarine blue, as a method to improve luminance without significantly damaging the fading of ultramarine blue during the cathode ray tube manufacturing process, a little less than 30% cobalt blue pigment is mixed with ultramarine pigment as disclosed in Japanese Patent Application Laid-Open No. 57-207675. 6 However, recently, in order to obtain even higher quality CRTs for color televisions, there has been a demand for improvements in the phosphor, such as: ■ Increased contrast (■ dense fluorescence), formation of haze, and ■ Improved life characteristics. has been done. In other words, regarding the contrast characteristics of the pigment-coated phosphor powder in the contrast characteristics of (■), when the pigment concentration is kept constant, it is best to use ultramarine alone, which has excellent reflectance and coloring power, and cobalt blue pigment is better compared to that. Far inferior. Therefore, 1- for Gunjo and Koba.
When a mixture of both blue pigments is used, the contrast deteriorates as the amount of cobalt blue pigment in the total pigment increases.

Further, when the contrast is kept constant, ultramarine blue with a lower pigment concentration coated on the phosphor has higher brightness, and when both are mixed, the brightness decreases as the amount of cobalt blue pigment increases. However, when used on a cathode ray tube, the ultramarine blue color fades as mentioned above, and so
The phosphor of the publication is more advantageous in terms of brightness and contrast. (2) In forming a dense phosphor film, it goes without saying that the denser the phosphor film is, the more the amount of phosphor in a given area is larger, the more advantageous it is in terms of luminance characteristics. If the phosphor film has a rough surface and has pinhole-like holes, not only will the luminance of the emitted light decrease, but the phosphor applied in the next process will easily enter the pinholes, causing color mixing and causing the blue color to fade. When the phosphors emit light, they emit light at the same time, leading to a decline in the quality of the cathode ray tube. In order to form a dense phosphor film, it is necessary to improve the dispersibility of the phosphor. Dispersion such as bead milling is required to disperse the phosphor, but if bead milling is performed for a long time, the brightness will decrease.

In order to achieve dispersion with as little bead milling as possible in the phosphor manufacturing process, it is possible to obtain a phosphor with better dispersibility by reducing the amount of adhesive used to coat the surface of the phosphor with the pigment as much as possible. However, the amount of adhesive used is proportional to the surface area of the pigment, and if the concentration of the pigment is kept constant and only the amount of adhesive is decreased in order to improve the dispersibility of the phosphor, the pigment will peel off. Considering such a fluorescent film and the above-mentioned contrast, Japanese Patent Application Laid-Open No. 57-207675 is very superior. However, considering the improvement in the life characteristics of cathode ray tubes, even though it is better than ultramarine alone, there is a need for further improvements in characteristics.

[Purpose of the invention]

By optimizing the mixing ratio of ultramarine and cobalt blue pigments, the present invention not only provides a high-quality color cathode ray tube with high contrast and dense phosphor film formation, but also provides a blue pigment-coated phosphor with excellent life characteristics. The purpose is to

[Summary of the invention]

The present invention is a blue pigment-coated phosphor coated with ultramarine and cobalt blue pigments, characterized in that the cobalt blue pigment is within a range of 30 to 70 percent by weight of the total pigment. If it is less than 30%, the life of Color Brown as a phosphor screen will not be sufficient. If it exceeds 70%, a large amount of pigment will be coated in order to obtain a certain contrast, and peeling will easily occur when preparing a phosphor slurry. Cobalt blue pigment accounts for 43 to 56 of total pigments
Most preferably, it is within the range of % by weight.

From the viewpoint of brightness and contrast I~, the amount of pigment coating is preferably within the range of 43.5 to 10% by weight of the total pigment, and 2 to 7% by weight of the total pigment.
Most preferably within the weight percent range.

Phosphors suitable for the present invention are ZnS:AgCQ and Z
nS: AgAQ, etc.

Figure 1 shows the proportion of cobalt blue pigment in a mixed pigment of ultramarine pigment and cobalt blue pigment, and the Z
nS: This is a diagram showing the relationship with relative brightness when a pigment-coated phosphor in which AgCQ phosphor is coated with 2% by weight is used in a color cathode ray tube.

Curve (a) is color cathode ray tube operation 0 hours 1 curve (b)
is the characteristic after 1000 hours, and curve (C) is the characteristic after 2000 hours.

As this figure shows, at 0 hours, the relative brightness is relatively high when the proportion of cobalt blue pigment is small, but at 1000 hours and 2000 hours, the relative brightness is large when the proportion of cobalt blue pigment is large. Cobalt blue pigment shows practical properties at 30% by weight.

[Embodiments of the invention]

Example [1] Weigh 100 g of ultramarine blue, disperse it in pure water, and add the entire amount to Ii.
Make it l. Weigh 00 g of cobalt aluminate i and disperse it in pure water, making the total amount 10. These solutions are referred to as an ultramarine blue dispersion solution and a cobalt blue pigment solution.

Separately, 1 kg of silver and chlorine activated zinc sulfide phosphor was dispersed in IOR pure water, and while stirring, 200++tQ of ultramarine dispersion solution (21 g as #blue) was gradually added and stirred for 30 minutes.

Next, use polyacrylamide 0.1 as the adhesive between the phosphor and the pigment.
Gradually add 82 ml of Percent solution to make the ultramarine blue adhere to the surface of the phosphor. Next, cobalt blue pigment solution 210a
Gradually add Q (21g as cobalt blue pigment) and add 82ml of 0.1% polyacrylamide solution.
Q is added in the same way as ultramarine blue to attach cobalt blue pigment to the surface of the phosphor. The phosphor is washed with pure water and dispersed for 20 minutes using glass beads, then dried and sieved. The thus obtained phosphor is a blue pigment-coated phosphor in which the pigment coverage in the phosphor is 4.2% by weight and the concentration of cobalt blue pigment in the total pigment is 50% by weight.

Polyvinyl alcohol, dichromate, and a dispersant are added to this to prepare a phosphor slurry, which is then applied. Next, we produced a prototype cathode ray tube through the normal cathode ray tube manufacturing process and conducted a life test. As shown in Table 1, the phosphor obtained in Example [13] provided a high-quality phosphor film and was excellent in the life test.

Examples [2] to [7] A cathode ray tube was made using a prototype phosphor manufactured by changing the pigment concentration and resin amount using the same manufacturing process as in Example [1], and a life test was conducted on Nira's phosphors. As shown in Table 1, a high-quality fluorescent film was obtained and the product was excellent in the life test.

For comparison of Examples (1) to [7], JP-A-57-20
Blending ratio where the concentration of cobalt blue pigment in ultramarine blue is 33.3% as shown in Publication No. 7675 (in other words, cobalt blue face F in all pigments according to the present invention) 1
Prototypes were produced by changing the pigment concentration so that the reflectance was the same as in each example at a reflectance of 25% 1~). In addition, in terms of luminance τ, a sample coated with ultramarine alone was manufactured to have the same reflectance as the example, and after 1000 hours,
This is a relative comparison when the luminance at a life time after 2000 hours is set as 100.

〔Effect of the invention〕

As explained above, the blue pigment-coated phosphor of the present invention is particularly effective in life tests and is particularly excellent as a blue-coated phosphor for color cathode ray tubes.

In Table 1, in Examples (1), (2), and [3], when a cathode ray tube was prototyped using a phosphor not coated with pigment, the relative value was 50 when the outside light reflectance of the cathode ray tube was taken as 100. Percent time.

(4) and (5) are when the external light reflectance relative value is 60 percent.

(6) and [7] are 42.5% of the time. The brightness in the life characteristics is the initial value of the ultramarine-coated phosphor alone, the brightness after 1000 hours, and the brightness after 2000 hours as 10.
This is the relative brightness when it is set to 0. As shown in this example [Table 1], the characteristics of the cathode ray tube phosphor in high contrast were able to improve the life characteristics without significantly impairing the density of the film.

Margin below

[Brief explanation of drawings]

Figure 1 shows the relationship between the proportion of cobalt pigment in a mixed pigment of ultramarine pigment and cobalt blue pigment and the relative brightness when a ZnS:Ag(4) phosphor coated with 2% by weight of the mixed pigment is used in a color cathode ray tube. This is a diagram showing the following: Agent: Patent Attorney: Nori Chika, Yudo, Norio Ogo

Claims (5)

[Claims] (1) In a blue pigmented phosphor coated with ultramarine and cobalt blue pigments, the cobalt blue pigment accounts for 3% of the total pigments.
A blue pigment coated phosphor characterized in that it is within the range of 0 to 70 weight percent. (2) Cobalt blue pigment accounts for 43.0 to 5 of all pigments.
A blue pigment-coated phosphor according to claim 1, characterized in that the amount is within the range of 6.0 weight percent. (3) The blue pigment-coated phosphor according to claim 1, wherein the amount of pigment coating is within the range of 0.5 to 10.0 weight percent based on the coated phosphor. (4) The blue pigment-coated phosphor according to claim 1, wherein the amount of pigment coated is within the range of 2 to 7 weight percent based on the weight of the phosphor coated. (5) The blue pigment-coated phosphor according to claim 1, wherein the phosphor is a zinc sulfide phosphor activated with either silver and chlorine or silver and aluminum.